diff options
28 files changed, 6947 insertions, 0 deletions
diff --git a/include/llvm/Analysis/Passes.h b/include/llvm/Analysis/Passes.h index 0eff75fe2f..a22bd12dec 100644 --- a/include/llvm/Analysis/Passes.h +++ b/include/llvm/Analysis/Passes.h @@ -88,6 +88,13 @@ namespace llvm { //===--------------------------------------------------------------------===// // + // createObjCARCAliasAnalysisPass - This pass implements ObjC-ARC-based + // alias analysis. + // + ImmutablePass *createObjCARCAliasAnalysisPass(); + + //===--------------------------------------------------------------------===// + // // createProfileLoaderPass - This pass loads information from a profile dump // file. // diff --git a/include/llvm/InitializePasses.h b/include/llvm/InitializePasses.h index 372eaba74a..de58252117 100644 --- a/include/llvm/InitializePasses.h +++ b/include/llvm/InitializePasses.h @@ -160,6 +160,10 @@ void initializeModuleDebugInfoPrinterPass(PassRegistry&); void initializeNoAAPass(PassRegistry&); void initializeNoProfileInfoPass(PassRegistry&); void initializeNoPathProfileInfoPass(PassRegistry&); +void initializeObjCARCAliasAnalysisPass(PassRegistry&); +void initializeObjCARCExpandPass(PassRegistry&); +void initializeObjCARCContractPass(PassRegistry&); +void initializeObjCARCOptPass(PassRegistry&); void initializeOptimalEdgeProfilerPass(PassRegistry&); void initializeOptimizePHIsPass(PassRegistry&); void initializePEIPass(PassRegistry&); diff --git a/include/llvm/LinkAllPasses.h b/include/llvm/LinkAllPasses.h index c02e1615de..c2ea8efb9a 100644 --- a/include/llvm/LinkAllPasses.h +++ b/include/llvm/LinkAllPasses.h @@ -97,6 +97,10 @@ namespace { (void) llvm::createLowerSwitchPass(); (void) llvm::createNoAAPass(); (void) llvm::createNoProfileInfoPass(); + (void) llvm::createObjCARCAliasAnalysisPass(); + (void) llvm::createObjCARCExpandPass(); + (void) llvm::createObjCARCContractPass(); + (void) llvm::createObjCARCOptPass(); (void) llvm::createProfileEstimatorPass(); (void) llvm::createProfileVerifierPass(); (void) llvm::createPathProfileVerifierPass(); diff --git a/include/llvm/Support/PassManagerBuilder.h b/include/llvm/Support/PassManagerBuilder.h index 513bb887a0..31624db813 100644 --- a/include/llvm/Support/PassManagerBuilder.h +++ b/include/llvm/Support/PassManagerBuilder.h @@ -188,6 +188,7 @@ public: MPM.add(createArgumentPromotionPass()); // Scalarize uninlined fn args // Start of function pass. + MPM.add(createObjCARCExpandPass()); // Canonicalize ObjC ARC code. // Break up aggregate allocas, using SSAUpdater. MPM.add(createScalarReplAggregatesPass(-1, false)); MPM.add(createEarlyCSEPass()); // Catch trivial redundancies @@ -223,6 +224,7 @@ public: MPM.add(createJumpThreadingPass()); // Thread jumps MPM.add(createCorrelatedValuePropagationPass()); MPM.add(createDeadStoreEliminationPass()); // Delete dead stores + MPM.add(createObjCARCOptPass()); // Objective-C ARC optimizations. MPM.add(createAggressiveDCEPass()); // Delete dead instructions MPM.add(createCFGSimplificationPass()); // Merge & remove BBs MPM.add(createInstructionCombiningPass()); // Clean up after everything. diff --git a/include/llvm/Transforms/Scalar.h b/include/llvm/Transforms/Scalar.h index de46a8d984..e830435751 100644 --- a/include/llvm/Transforms/Scalar.h +++ b/include/llvm/Transforms/Scalar.h @@ -338,6 +338,24 @@ Pass *createCorrelatedValuePropagationPass(); //===----------------------------------------------------------------------===// // +// ObjCARCExpand - ObjC ARC preliminary simplifications. +// +Pass *createObjCARCExpandPass(); + +//===----------------------------------------------------------------------===// +// +// ObjCARCContract - Late ObjC ARC cleanups. +// +Pass *createObjCARCContractPass(); + +//===----------------------------------------------------------------------===// +// +// ObjCARCOpt - ObjC ARC optimization. +// +Pass *createObjCARCOptPass(); + +//===----------------------------------------------------------------------===// +// // InstructionSimplifier - Remove redundant instructions. // FunctionPass *createInstructionSimplifierPass(); diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp index 589d0a9a67..b98fbed695 100644 --- a/lib/CodeGen/LLVMTargetMachine.cpp +++ b/lib/CodeGen/LLVMTargetMachine.cpp @@ -303,6 +303,10 @@ bool LLVMTargetMachine::addCommonCodeGenPasses(PassManagerBase &PM, if (!DisableVerify) PM.add(createVerifierPass()); + // Simplify ObjC ARC code. This is done late because it makes re-optimization + // difficult. + PM.add(createObjCARCContractPass()); + // Run loop strength reduction before anything else. if (OptLevel != CodeGenOpt::None && !DisableLSR) { PM.add(createLoopStrengthReducePass(getTargetLowering())); diff --git a/lib/Transforms/Scalar/CMakeLists.txt b/lib/Transforms/Scalar/CMakeLists.txt index fcf914f8ba..c223da60e0 100644 --- a/lib/Transforms/Scalar/CMakeLists.txt +++ b/lib/Transforms/Scalar/CMakeLists.txt @@ -20,6 +20,7 @@ add_llvm_library(LLVMScalarOpts LoopUnswitch.cpp LowerAtomic.cpp MemCpyOptimizer.cpp + ObjCARC.cpp Reassociate.cpp Reg2Mem.cpp SCCP.cpp diff --git a/lib/Transforms/Scalar/ObjCARC.cpp b/lib/Transforms/Scalar/ObjCARC.cpp new file mode 100644 index 0000000000..e65e2853c2 --- /dev/null +++ b/lib/Transforms/Scalar/ObjCARC.cpp @@ -0,0 +1,3520 @@ +//===- ObjCARC.cpp - ObjC ARC Optimization --------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file defines ObjC ARC optimizations. ARC stands for +// Automatic Reference Counting and is a system for managing reference counts +// for objects in Objective C. +// +// The optimizations performed include elimination of redundant, partially +// redundant, and inconsequential reference count operations, elimination of +// redundant weak pointer operations, pattern-matching and replacement of +// low-level operations into higher-level operations, and numerous minor +// simplifications. +// +// This file also defines a simple ARC-aware AliasAnalysis. +// +// WARNING: This file knows about certain library functions. It recognizes them +// by name, and hardwires knowedge of their semantics. +// +// WARNING: This file knows about how certain Objective-C library functions are +// used. Naive LLVM IR transformations which would otherwise be +// behavior-preserving may break these assumptions. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "objc-arc" +#include "llvm/Function.h" +#include "llvm/Intrinsics.h" +#include "llvm/GlobalVariable.h" +#include "llvm/DerivedTypes.h" +#include "llvm/Analysis/ValueTracking.h" +#include "llvm/Transforms/Utils/Local.h" +#include "llvm/Support/CallSite.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/ADT/StringSwitch.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/STLExtras.h" +using namespace llvm; + +// A handy option to enable/disable all optimizations in this file. +static cl::opt<bool> EnableARCOpts("enable-objc-arc-opts", cl::init(true)); + +//===----------------------------------------------------------------------===// +// Misc. Utilities +//===----------------------------------------------------------------------===// + +namespace { + /// MapVector - An associative container with fast insertion-order + /// (deterministic) iteration over its elements. Plus the special + /// blot operation. + template<class KeyT, class ValueT> + class MapVector { + /// Map - Map keys to indices in Vector. + typedef DenseMap<KeyT, size_t> MapTy; + MapTy Map; + + /// Vector - Keys and values. + typedef std::vector<std::pair<KeyT, ValueT> > VectorTy; + VectorTy Vector; + + public: + typedef typename VectorTy::iterator iterator; + typedef typename VectorTy::const_iterator const_iterator; + iterator begin() { return Vector.begin(); } + iterator end() { return Vector.end(); } + const_iterator begin() const { return Vector.begin(); } + const_iterator end() const { return Vector.end(); } + +#ifdef XDEBUG + ~MapVector() { + assert(Vector.size() >= Map.size()); // May differ due to blotting. + for (typename MapTy::const_iterator I = Map.begin(), E = Map.end(); + I != E; ++I) { + assert(I->second < Vector.size()); + assert(Vector[I->second].first == I->first); + } + for (typename VectorTy::const_iterator I = Vector.begin(), + E = Vector.end(); I != E; ++I) + assert(!I->first || + (Map.count(I->first) && + Map[I->first] == size_t(I - Vector.begin()))); + } +#endif + + ValueT &operator[](KeyT Arg) { + std::pair<typename MapTy::iterator, bool> Pair = + Map.insert(std::make_pair(Arg, size_t(0))); + if (Pair.second) { + Pair.first->second = Vector.size(); + Vector.push_back(std::make_pair(Arg, ValueT())); + return Vector.back().second; + } + return Vector[Pair.first->second].second; + } + + std::pair<iterator, bool> + insert(const std::pair<KeyT, ValueT> &InsertPair) { + std::pair<typename MapTy::iterator, bool> Pair = + Map.insert(std::make_pair(InsertPair.first, size_t(0))); + if (Pair.second) { + Pair.first->second = Vector.size(); + Vector.push_back(InsertPair); + return std::make_pair(llvm::prior(Vector.end()), true); + } + return std::make_pair(Vector.begin() + Pair.first->second, false); + } + + const_iterator find(KeyT Key) const { + typename MapTy::const_iterator It = Map.find(Key); + if (It == Map.end()) return Vector.end(); + return Vector.begin() + It->second; + } + + /// blot - This is similar to erase, but instead of removing the element + /// from the vector, it just zeros out the key in the vector. This leaves + /// iterators intact, but clients must be prepared for zeroed-out keys when + /// iterating. + void blot(KeyT Key) { + typename MapTy::iterator It = Map.find(Key); + if (It == Map.end()) return; + Vector[It->second].first = KeyT(); + Map.erase(It); + } + + void clear() { + Map.clear(); + Vector.clear(); + } + }; +} + +//===----------------------------------------------------------------------===// +// ARC Utilities. +//===----------------------------------------------------------------------===// + +namespace { + /// InstructionClass - A simple classification for instructions. + enum InstructionClass { + IC_Retain, ///< objc_retain + IC_RetainRV, ///< objc_retainAutoreleasedReturnValue + IC_RetainBlock, ///< objc_retainBlock + IC_Release, ///< objc_release + IC_Autorelease, ///< objc_autorelease + IC_AutoreleaseRV, ///< objc_autoreleaseReturnValue + IC_AutoreleasepoolPush, ///< objc_autoreleasePoolPush + IC_AutoreleasepoolPop, ///< objc_autoreleasePoolPop + IC_NoopCast, ///< objc_retainedObject, etc. + IC_FusedRetainAutorelease, ///< objc_retainAutorelease + IC_FusedRetainAutoreleaseRV, ///< objc_retainAutoreleaseReturnValue + IC_LoadWeakRetained, ///< objc_loadWeakRetained (primitive) + IC_StoreWeak, ///< objc_storeWeak (primitive) + IC_InitWeak, ///< objc_initWeak (derived) + IC_LoadWeak, ///< objc_loadWeak (derived) + IC_MoveWeak, ///< objc_moveWeak (derived) + IC_CopyWeak, ///< objc_copyWeak (derived) + IC_DestroyWeak, ///< objc_destroyWeak (derived) + IC_CallOrUser, ///< could call objc_release and/or "use" pointers + IC_Call, ///< could call objc_release + IC_User, ///< could "use" a pointer + IC_None ///< anything else + }; +} + +/// IsPotentialUse - Test whether the given value is possible a +/// reference-counted pointer. +static bool IsPotentialUse(const Value *Op) { + // Pointers to static or stack storage are not reference-counted pointers. + if (isa<Constant>(Op) || isa<AllocaInst>(Op)) + return false; + // Special arguments are not reference-counted. + if (const Argument *Arg = dyn_cast<Argument>(Op)) + if (Arg->hasByValAttr() || + Arg->hasNestAttr() || + Arg->hasStructRetAttr()) + return false; + // Only consider values with pointer types, and not function pointers. + const PointerType *Ty = dyn_cast<PointerType>(Op->getType()); + if (!Ty || isa<FunctionType>(Ty->getElementType())) + return false; + // Conservatively assume anything else is a potential use. + return true; +} + +/// GetCallSiteClass - Helper for GetInstructionClass. Determines what kind +/// of construct CS is. +static InstructionClass GetCallSiteClass(ImmutableCallSite CS) { + for (ImmutableCallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); + I != E; ++I) + if (IsPotentialUse(*I)) + return CS.onlyReadsMemory() ? IC_User : IC_CallOrUser; + + return CS.onlyReadsMemory() ? IC_None : IC_Call; +} + +/// GetFunctionClass - Determine if F is one of the special known Functions. +/// If it isn't, return IC_CallOrUser. +static InstructionClass GetFunctionClass(const Function *F) { + Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end(); + + // No arguments. + if (AI == AE) + return StringSwitch<InstructionClass>(F->getName()) + .Case("objc_autoreleasePoolPush", IC_AutoreleasepoolPush) + .Default(IC_CallOrUser); + + // One argument. + const Argument *A0 = AI++; + if (AI == AE) + // Argument is a pointer. + if (const PointerType *PTy = dyn_cast<PointerType>(A0->getType())) { + const Type *ETy = PTy->getElementType(); + // Argument is i8*. + if (ETy->isIntegerTy(8)) + return StringSwitch<InstructionClass>(F->getName()) + .Case("objc_retain", IC_Retain) + .Case("objc_retainAutoreleasedReturnValue", IC_RetainRV) + .Case("objc_retainBlock", IC_RetainBlock) + .Case("objc_release", IC_Release) + .Case("objc_autorelease", IC_Autorelease) + .Case("objc_autoreleaseReturnValue", IC_AutoreleaseRV) + .Case("objc_autoreleasePoolPop", IC_AutoreleasepoolPop) + .Case("objc_retainedObject", IC_NoopCast) + .Case("objc_unretainedObject", IC_NoopCast) + .Case("objc_unretainedPointer", IC_NoopCast) + .Case("objc_retain_autorelease", IC_FusedRetainAutorelease) + .Case("objc_retainAutorelease", IC_FusedRetainAutorelease) + .Case("objc_retainAutoreleaseReturnValue",IC_FusedRetainAutoreleaseRV) + .Default(IC_CallOrUser); + + // Argument is i8** + if (const PointerType *Pte = dyn_cast<PointerType>(ETy)) + if (Pte->getElementType()->isIntegerTy(8)) + return StringSwitch<InstructionClass>(F->getName()) + .Case("objc_loadWeakRetained", IC_LoadWeakRetained) + .Case("objc_loadWeak", IC_LoadWeak) + .Case("objc_destroyWeak", IC_DestroyWeak) + .Default(IC_CallOrUser); + } + + // Two arguments, first is i8**. + const Argument *A1 = AI++; + if (AI == AE) + if (const PointerType *PTy = dyn_cast<PointerType>(A0->getType())) + if (const PointerType *Pte = dyn_cast<PointerType>(PTy->getElementType())) + if (Pte->getElementType()->isIntegerTy(8)) + if (const PointerType *PTy1 = dyn_cast<PointerType>(A1->getType())) { + const Type *ETy1 = PTy1->getElementType(); + // Second argument is i8* + if (ETy1->isIntegerTy(8)) + return StringSwitch<InstructionClass>(F->getName()) + .Case("objc_storeWeak", IC_StoreWeak) + .Case("objc_initWeak", IC_InitWeak) + .Default(IC_CallOrUser); + // Second argument is i8**. + if (const PointerType *Pte1 = dyn_cast<PointerType>(ETy1)) + if (Pte1->getElementType()->isIntegerTy(8)) + return StringSwitch<InstructionClass>(F->getName()) + .Case("objc_moveWeak", IC_MoveWeak) + .Case("objc_copyWeak", IC_CopyWeak) + .Default(IC_CallOrUser); + } + + // Anything else. + return IC_CallOrUser; +} + +/// GetInstructionClass - Determine what kind of construct V is. +static InstructionClass GetInstructionClass(const Value *V) { + if (const Instruction *I = dyn_cast<Instruction>(V)) { + // Any instruction other than bitcast and gep with a pointer operand have a + // use of an objc pointer. Bitcasts, GEPs, Selects, PHIs transfer a pointer + // to a subsequent use, rather than using it themselves, in this sense. + // As a short cut, several other opcodes are known to have no pointer + // operands of interest. And ret is never followed by a release, so it's + // not interesting to examine. + switch (I->getOpcode()) { + case Instruction::Call: { + const CallInst *CI = cast<CallInst>(I); + // Check for calls to special functions. + if (const Function *F = CI->getCalledFunction()) { + InstructionClass Class = GetFunctionClass(F); + if (Class != IC_CallOrUser) + return Class; + + // None of the intrinsic functions do objc_release. For intrinsics, the + // only question is whether or not they may be users. + switch (F->getIntrinsicID()) { + case 0: break; + case Intrinsic::bswap: case Intrinsic::ctpop: + case Intrinsic::ctlz: case Intrinsic::cttz: + case Intrinsic::returnaddress: case Intrinsic::frameaddress: + case Intrinsic::stacksave: case Intrinsic::stackrestore: + case Intrinsic::vastart: case Intrinsic::vacopy: case Intrinsic::vaend: + // Don't let dbg info affect our results. + case Intrinsic::dbg_declare: case Intrinsic::dbg_value: + // Short cut: Some intrinsics obviously don't use ObjC pointers. + return IC_None; + default: + for (Function::const_arg_iterator AI = F->arg_begin(), + AE = F->arg_end(); AI != AE; ++AI) + if (IsPotentialUse(AI)) + return IC_User; + return IC_None; + } + } + return GetCallSiteClass(CI); + } + case Instruction::Invoke: + return GetCallSiteClass(cast<InvokeInst>(I)); + case Instruction::BitCast: + case Instruction::GetElementPtr: + case Instruction::Select: case Instruction::PHI: + case Instruction::Ret: case Instruction::Br: + case Instruction::Switch: case Instruction::IndirectBr: + case Instruction::Alloca: case Instruction::VAArg: + case Instruction::Add: case Instruction::FAdd: + case Instruction::Sub: case Instruction::FSub: + case Instruction::Mul: case Instruction::FMul: + case Instruction::SDiv: case Instruction::UDiv: case Instruction::FDiv: + case Instruction::SRem: case Instruction::URem: case Instruction::FRem: + case Instruction::Shl: case Instruction::LShr: case Instruction::AShr: + case Instruction::And: case Instruction::Or: case Instruction::Xor: + case Instruction::SExt: case Instruction::ZExt: case Instruction::Trunc: + case Instruction::IntToPtr: case Instruction::FCmp: + case Instruction::FPTrunc: case Instruction::FPExt: + case Instruction::FPToUI: case Instruction::FPToSI: + case Instruction::UIToFP: case Instruction::SIToFP: + case Instruction::InsertElement: case Instruction::ExtractElement: + case Instruction::ShuffleVector: + case Instruction::ExtractValue: + break; + case Instruction::ICmp: + // Comparing a pointer with null, or any other constant, isn't an + // interesting use, because we don't care what the pointer points to, or + // about the values of any other dynamic reference-counted pointers. + if (IsPotentialUse(I->getOperand(1))) + return IC_User; + break; + default: + // For anything else, check all the operands. + for (User::const_op_iterator OI = I->op_begin(), OE = I->op_end(); + OI != OE; ++OI) + if (IsPotentialUse(*OI)) + return IC_User; + } + } + + // Otherwise, it's totally inert for ARC purposes. + return IC_None; +} + +/// GetBasicInstructionClass - Determine what kind of construct V is. This is +/// similar to GetInstructionClass except that it only detects objc runtine +/// calls. This allows it to be faster. +static InstructionClass GetBasicInstructionClass(const Value *V) { + if (const CallInst *CI = dyn_cast<CallInst>(V)) { + if (const Function *F = CI->getCalledFunction()) + return GetFunctionClass(F); + // Otherwise, be conservative. + return IC_CallOrUser; + } + + // Otherwise, be conservative. + return IC_User; +} + +/// IsRetain - Test if the the given class is objc_retain or +/// equivalent. +static bool IsRetain(InstructionClass Class) { + return Class == IC_Retain || + Class == IC_RetainRV; +} + +/// IsAutorelease - Test if the the given class is objc_autorelease or +/// equivalent. +static bool IsAutorelease(InstructionClass Class) { + return Class == IC_Autorelease || + Class == IC_AutoreleaseRV; +} + +/// IsForwarding - Test if the given class represents instructions which return +/// their argument verbatim. +static bool IsForwarding(InstructionClass Class) { + // objc_retainBlock technically doesn't always return its argument + // verbatim, but it doesn't matter for our purposes here. + return Class == IC_Retain || + Class == IC_RetainRV || + Class == IC_Autorelease || + Class == IC_AutoreleaseRV || + Class == IC_RetainBlock || + Class == IC_NoopCast; +} + +/// IsNoopOnNull - Test if the given class represents instructions which do +/// nothing if passed a null pointer. +static bool IsNoopOnNull(InstructionClass Class) { + return Class == IC_Retain || + Class == IC_RetainRV || + Class == IC_Release || + Class == IC_Autorelease || + Class == IC_AutoreleaseRV || + Class == IC_RetainBlock; +} + +/// IsAlwaysTail - Test if the given class represents instructions which are +/// always safe to mark with the "tail" keyword. +static bool IsAlwaysTail(InstructionClass Class) { + // IC_RetainBlock may be given a stack argument. + return Class == IC_Retain || + Class == IC_RetainRV || + Class == IC_Autorelease || + Class == IC_AutoreleaseRV; +} + +/// IsNoThrow - Test if the given class represents instructions which are always +/// safe to mark with the nounwind attribute.. +static bool IsNoThrow(InstructionClass Class) { + return Class == IC_Retain || + Class == IC_RetainRV || + Class == IC_RetainBlock || + Class == IC_Release || + Class == IC_Autorelease || + Class == IC_AutoreleaseRV || + Class == IC_AutoreleasepoolPush || + Class == IC_AutoreleasepoolPop; +} + +/// EraseInstruction - Erase the given instruction. ObjC calls return their +/// argument verbatim, so if it's such a call and the return value has users, +/// replace them with the argument value. +static void EraseInstruction(Instruction *CI) { + Value *OldArg = cast<CallInst>(CI)->getArgOperand(0); + + bool Unused = CI->use_empty(); + + if (!Unused) { + // Replace the return value with the argument. + assert(IsForwarding(GetBasicInstructionClass(CI)) && + "Can't delete non-forwarding instruction with users!"); + CI->replaceAllUsesWith(OldArg); + } + + CI->eraseFromParent(); + + if (Unused) + RecursivelyDeleteTriviallyDeadInstructions(OldArg); +} + +/// GetUnderlyingObjCPtr - This is a wrapper around getUnderlyingObject which +/// also knows how to look through objc_retain and objc_autorelease calls, which +/// we know to return their argument verbatim. +static const Value *GetUnderlyingObjCPtr(const Value *V) { + for (;;) { + V = GetUnderlyingObject(V); + if (!IsForwarding(GetBasicInstructionClass(V))) + break; + V = cast<CallInst>(V)->getArgOperand(0); + } + + return V; +} + +/// StripPointerCastsAndObjCCalls - This is a wrapper around +/// Value::stripPointerCasts which also knows how to look through objc_retain +/// and objc_autorelease calls, which we know to return their argument verbatim. +static const Value *StripPointerCastsAndObjCCalls(const Value *V) { + for (;;) { + V = V->stripPointerCasts(); + if (!IsForwarding(GetBasicInstructionClass(V))) + break; + V = cast<CallInst>(V)->getArgOperand(0); + } + return V; +} + +/// StripPointerCastsAndObjCCalls - This is a wrapper around +/// Value::stripPointerCasts which also knows how to look through objc_retain +/// and objc_autorelease calls, which we know to return their argument verbatim. +static Value *StripPointerCastsAndObjCCalls(Value *V) { + for (;;) { + V = V->stripPointerCasts(); + if (!IsForwarding(GetBasicInstructionClass(V))) + break; + V = cast<CallInst>(V)->getArgOperand(0); + } + return V; +} + +/// GetObjCArg - Assuming the given instruction is one of the special calls such +/// as objc_retain or objc_release, return the argument value, stripped of no-op +/// casts and forwarding calls. +static Value *GetObjCArg(Value *Inst) { + return StripPointerCastsAndObjCCalls(cast<CallInst>(Inst)->getArgOperand(0)); +} + +/// IsObjCIdentifiedObject - This is similar to AliasAnalysis' +/// isObjCIdentifiedObject, except that it uses special knowledge of +/// ObjC conventions... +static bool IsObjCIdentifiedObject(const Value *V) { + // Assume that call results and arguments have their own "provenance". + // Constants (including GlobalVariables) and Allocas are never + // reference-counted. + if (isa<CallInst>(V) || isa<InvokeInst>(V) || + isa<Argument>(V) || isa<Constant>(V) || + isa<AllocaInst>(V)) + return true; + + if (const LoadInst *LI = dyn_cast<LoadInst>(V)) { + const Value *Pointer = + StripPointerCastsAndObjCCalls(LI->getPointerOperand()); + if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(Pointer)) { + StringRef Name = GV->getName(); + // These special variables are known to hold values which are not + // reference-counted pointers. + if (Name.startswith("\01L_OBJC_SELECTOR_REFERENCES_") || + Name.startswith("\01L_OBJC_CLASSLIST_REFERENCES_") || + Name.startswith("\01L_OBJC_CLASSLIST_SUP_REFS_$_") || + Name.startswith("\01L_OBJC_METH_VAR_NAME_") || + Name.startswith("\01l_objc_msgSend_fixup_")) + return true; + } + } + + return false; +} + +/// FindSingleUseIdentifiedObject - This is similar to +/// StripPointerCastsAndObjCCalls but it stops as soon as it finds a value +/// with multiple uses. +static const Value *FindSingleUseIdentifiedObject(const Value *Arg) { + if (Arg->hasOneUse()) { + if (const BitCastInst *BC = dyn_cast<BitCastInst>(Arg)) + return FindSingleUseIdentifiedObject(BC->getOperand(0)); + if (const GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Arg)) + if (GEP->hasAllZeroIndices()) + return FindSingleUseIdentifiedObject(GEP->getPointerOperand()); + if (IsForwarding(GetBasicInstructionClass(Arg))) + return FindSingleUseIdentifiedObject( + cast<CallInst>(Arg)->getArgOperand(0)); + if (!IsObjCIdentifiedObject(Arg)) + return 0; + return Arg; + } + + // If we found an identifiable object but it has multiple uses, but they + // are trivial uses, we can still consider this to be a single-use + // value. + if (IsObjCIdentifiedObject(Arg)) { + for (Value::const_use_iterator UI = Arg->use_begin(), UE = Arg->use_end(); + UI != UE; ++UI) { + const User *U = *UI; + if (!U->use_empty() || StripPointerCastsAndObjCCalls(U) != Arg) + return 0; + } + + return Arg; + } + + return 0; +} + +//===----------------------------------------------------------------------===// +// ARC AliasAnalysis. +//===----------------------------------------------------------------------===// + +#include "llvm/Pass.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/Analysis/Passes.h" + +namespace { + /// ObjCARCAliasAnalysis - This is a simple alias analysis + /// implementation that uses knowledge of ARC constructs to answer queries. + /// + /// TODO: This class could be generalized to know about other ObjC-specific + /// tricks. Such as knowing that ivars in the non-fragile ABI are non-aliasing + /// even though their offsets are dynamic. + class ObjCARCAliasAnalysis : public ImmutablePass, + public AliasAnalysis { + public: + static char ID; // Class identification, replacement for typeinfo + ObjCARCAliasAnalysis() : ImmutablePass(ID) { + initializeObjCARCAliasAnalysisPass(*PassRegistry::getPassRegistry()); + } + + private: + virtual void initializePass() { + InitializeAliasAnalysis(this); + } + + /// getAdjustedAnalysisPointer - This method is used when a pass implements + /// an analysis interface through multiple inheritance. If needed, it + /// should override this to adjust the this pointer as needed for the + /// specified pass info. + virtual void *getAdjustedAnalysisPointer(const void *PI) { + if (PI == &AliasAnalysis::ID) + return (AliasAnalysis*)this; + return this; + } + + virtual void getAnalysisUsage(AnalysisUsage & |